1. Field of the Invention
The present invention relates to an ultraviolet irradiator for irradiating ultraviolet light (ultraviolet ray), and an ultraviolet irradiating apparatus in which the ultraviolet irradiator is freely incorporated.
2. Description of the Related Art
There is known an ultraviolet irradiating apparatus having a built-in type ultraviolet irradiator which irradiates a sample mounted in a sample chamber with ultraviolet light emitted from the ultraviolet irradiator. This type of ultraviolet irradiating apparatus has been broadly used for weather resistant tests of samples, surface cleaning, reforming, etc. (see JP-A-2002-191965 and JP-A-10-104151, for example).
This type of ultraviolet irradiator has an ultraviolet lamp, a colored glass filter which is disposed so as to surround the ultraviolet lamp and transmits therethrough only a desired ultraviolet region component out of various kinds of light components emitted from the ultraviolet lamp, and a reflection plate for reflecting light emitted from the ultraviolet lamp.
Considering such a situation that the surface temperature of the ultraviolet lamp reaches a high temperature near to 1000° C. when the ultraviolet lamp is turned on, the ultraviolet lamp is mounted in a water-cooling jacket formed of quartz glass to cool the ultraviolet lamp. Furthermore, even the colored glass filter is generally mounted in the water-cooling jacket because it is exposed to light of the ultraviolet lamp and absorbs various light components other than the desired ultraviolet light component (a visible region component and an infrared region component, for example), so that the colored glass filter itself is heated. The colored glass filter is normally fixed in the water-cooling jacket to prevent occurrence of water leakage, and thus the colored glass filter and the water-cooling jacket are unified (see JP-A-10-104151 and JP-A-6-267509, for example).
In these ultraviolet irradiators, when the colored glass filter is deteriorated by ultraviolet light of the ultraviolet lamp and thus the transmissivity of the colored glass filter decreases, the illuminance of the ultraviolet irradiator is lowered due to the decrease of the transmissivity of the colored glass filter. In such a case, however, the colored glass filter must be exchanged by a new one together with the water-cooling jacket because the colored glass filter and the water-cooling jacket are unified. In this case, the water-cooling jacket which has not yet been deteriorated by ultraviolet light must be simultaneously exchanged by a new one, and this is a problem from the view point of running cost.